Faucet valves that incorporate sliding ceramic plates have many advantages over other types of faucet valves. The ceramic elements are durable and provide for long life with virtually no leakage between the two highly polished valving surfaces of the respective ceramic valve elements. However, in order for the ceramic valves to work in the faucet environment, the valves must be slidable under compressive force. Commonly, this compressive force is obtained by having the lower stationary valve member seated on resilient elastomeric seals. The upper portion of the valve must have all its elements dimensioned precisely so that the movable valve element will be under compressive force. Manufacturing tolerances have to be within a certain range in order for the resilient elastomeric seal to function properly. If the total height of the internal valve members is too great, the elastomeric seal becomes overly compressed and the ceramic valve members are pressed against each other with too great a force and are therefore hard to operate.
On the other hand, if the total height of the internal valve members is too little, the resilient elastomeric seal pushes the fixed valve element fully upward; however, the two ceramic valve members are still not adequately pressed together so that leakage between the fixed ceramic plate and the movable top ceramic plate still occurs.
Hydraulic pressure can be used to press the stationary valve up against the ceramic valve plate. Hydraulic pressure is used to press ceramic plates together in a faucet valve disclosed in my U.S. Pat. No. 4,250,912 issued on Feb. 17, 1981 entitled "A Faucet Valve".
However, in single handle mixing valves it must be assured that the hydraulic pressure not only pushes the cartridge portion upward to press the fixed plate against the movable plate, but also that separation between the cartridge lower section and the fixed plate does not occur due to the same hydraulic pressures.